Have you thought of a clone doing all your chores at home while you are busy at office or gone out with friends?? You may think it is really awesome to have one. So let’s look into this process of producing clones, cloning.
Cloning is the process in which an organism is created with the exact genetic copy of another organism. Even among us there are human clones, not made in lab but occurred naturally. Something you won’t believe at once but think a while about the identical twins.
How can we make an exact copy of an organism in laboratories? There are two ways used in this; Artificial Embryo Twinning and Somatic Cell Nuclear Transfer.
Artificial embryo twinning is a relatively low-tech version and it imitates the natural process of creating identical twins. In nature after the fertilization of an egg and a sperm rarely the resultant zygote divide into two-celled embryo, two cells separate and each continues to divide separately and that result in two individuals in mother’s womb. As the two cells are from the same zygote the individuals are genetically identical. This method is used here and it happens in a petri dish. The individual cells separated from the zygote are allowed to divide and develop and then they are placed in a womb of a surrogate mother where they are carried and delivered.
Somatic cell transfer uses a different method and this method was used to create Dolly, the sheep. In here the scientists had isolated a somatic cell (any cell in the body other than the reproductive cells) and transferred the nucleus of that to an egg cell in which the nucleus has been removed. The egg cell behaved exactly like a fertilized zygote after some chemical tweaks. The developed embryo was placed in a surrogate mother to be carried and delivered. Dolly was genetically identical with the adult female that donated the somatic cell nucleus and it was the first cloned mammal from an adult somatic cell. In the first method the zygote get the two sets of chromosomes from the egg cell and the sperm but in here both the sets are given by the somatic cell nucleus.
Why cloning is done? There are some usages related with this. This is widely used for medical purposes. Cloning animal models of disease to learn about human diseases are done by researchers mostly using mice. Genetically defined stem cells are cloned for research and medical purposes. Farm animals like cows, sheep and goats are genetically engineered to produce drugs or proteins useful in medicine. Cloning can be used in reviving endangered or extinct species. DNA preserved for millions of years that are obtained from fossils could be used in this if there is a closely related living species that could serve as a surrogate mother. So can we have dinosaurs on the planet again? Probably not. It’s not likely that dinosaur DNA could survive undamaged for a long time. But scientists have tried cloning species that became extinct recently using well preserved tissue samples. Cloning can be used in reproducing a deceased pet. Although this seems like a joke if you have money you could get back your pet again. Cloning method using for humans is still a controversial issue and some social, ethical and legal matters lie beneath that. Once it can be done that would be used to help infertile couples to have children and to replace a deceased child but there may be technical challenges and risks associated with this.
We are only heard of few things that worked out but there are many experiments that failed. Even in successful ones problems arose later. So let’s have a look to the risks in cloning.
There is a high failure rate in somatic cell transfer method. The success rate is around 0.1-3%. This may be due to incompatibility of the transferred nucleus and the enucleated egg, egg with a newly transferred nucleus may not begin to divide or develop properly, failure in implantation of the embryo into the surrogate mother and failure in pregnancy. Sometimes the problems arise in the later development of the successful clones. Cloned animals tend to be much bigger at birth than a normal animal this is known as Large Offspring Syndrome (LOS) where they have abnormally large organs which lead to problems in breathing, blood flow and others. Also clones without this syndrome has shown kidney or brain malformation and impaired immune system which causes problems in later life. Although the clones look like the original and they are genetically identical there is a problem whether the clone will express the right gene at right time and to avoid that scientists have to reprogram the nucleus where incomplete programming would cause abnormal gene expression patterns. Also there is some problems related with telomeric differences which still scientists aren’t sure why cloned animals show different telomere lengths.
Apart from the risks there lies some issues with cloning; ethical, legal and social issues where ethical issues lead to consider the potential of cloning, legal issues help policymakers to regulate the cloning technologies and social issues deal with the impacts on the society. With the issues comprising from these areas there would be questions that could be raised and all would base on the opinion we carry towards cloning.